Tropical cyclones (TCs) are posing growing threat to coastal populations and property, thereby necessitating more millennial paleoclimatic reconstructions. This study presents a 3100-year record from Marou Lagoon, Emau Island, Vanuatu. Using coarse anomalies as the main proxy, 36 intense tropical cyclones are identified (∼1.2/century). Active TC phases occurred during 1550–1750 CE, 350–750 CE, and the 20th century, contrasting with a pre-Common Era quiescent period. Comparative analysis with five paleotempestological records across the tropical South Pacific reveals multidecadal-to-centennial TC variability is dominantly governed by ENSO-driven shifts in the South Pacific Convergence Zone (SPCZ). La Niña-like periods cause southwestward SPCZ displacement and expansion, causing basin-wide enhanced cyclogenesis, while persistent strong El Niño conditions collapse the SPCZ into a zonal structure near French Polynesia, concentrating activity at eastern sites and suppressing western ones. Weak-to-moderate El Niño states exhibit stochastic dominance. Critically, sedimentological analysis reveals the most prominent event bed represents the cataclysmic Kuwae eruption in mid-15th. This deposit exhibits a five-stage sequence reflecting eruption progression, providing unprecedented resolution of eruption dynamics and tsunami impacts that surpass subaerial records. Typical diagnostic features of tsunami deposits (e.g., hummocky cross-stratification) are absent due to lagoon barrier/reef sheltering, and the heterogeneous density and shape of dominant pyroclastic materials (especially pumice) invalidate standard hydraulic grain-size models. This study demonstrates that sheltered lagoons preserve high-fidelity records of both extreme TCs and volcanogenic tsunamis. Such archives offer critical insights into regional climatic drivers and geohazard mechanisms but require environment-specific sedimentological frameworks, particularly where low-density pyroclastics dominate coarse fractions.
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